Common Variable Immunodeficiency: A Standardized Patient Case for Second-Year Medical Students

Common variable immunodeficiency (CVID) is the most common symptomatic antibody deficiency, with a prevalence of 0.6-6.9 depending on the population studied. In contrast to other primary immunodeficiency diseases (PIDDs), symptoms may not appear until the third decade of life. Lack of recognition of CVID is a persistent problem. Myriad confounding clinical phenotypes and frequent infections, including autoimmunity, malignancy, chronic lung disease, granulomatous disease, and gastrointestinal disease, complicate the diagnosis. Often it is years before a diagnosis is made, leading to irreversible morbidities and mortality.

Second-year medical students are introduced to CVID during their session on PIDDs that occurs during the immunology/rheumatology course. To assess students' recognition of CVID, a 15-minute OSCE encounter was created that included a simulation of lung sounds (rhonchi), physical exam cards (clubbing, otitis media with effusion), and moulage of skin (petechiae). A standardized patient (SP) portrayed a patient requesting antibiotics for a sinus infection. Students were tasked to both interview the patient and perform a hypothesis-driven physical exam. A postencounter exercise queried the students on their differential diagnosis and their rationale.

Item analysis of the case showed high levels of difficulty and strong discrimination between high- and low-performing students in both communication skills and clinical reasoning in CVID.

This SP encounter can be used in both formative and summative assessments to measure the recognition of CVID.